Sublethal Photothermal Stimulation with a Micropulse Laser Induces Heat Shock Protein Expression in ARPE-19 Cells

Figure 1

Experimental setup for laser irradiation of cultured cell layers. (a, b) A diode laser beam passed through a dichroic mirror to perpendicularly irradiate a full confluent cultured cell layer on a glass-based dish. To avoid blocking diode laser light, a phenol-red-free culture medium was used. (c) Confocal microscopy bright-field images of the irradiated cell layer. Spots were made using the continuous-wave mode with a power of 250 mW, duration of 500 ms, and spot size of 200 μm. The white dotted circle indicates the laser irradiation site. A video is also available (see Supplementary Material 1). (d) Two hours after laser irradiation (using the laser settings described in (c)), cell viability was assessed using LIVE/DEAD cell imaging reagents. Live cells were stained green, and dead cells were stained red. Fluorescent images were captured with confocal microscopy (projected images). Cells within the laser spot were dead, but cell groups forming the sparse annular intercellular spaces observed in the bright-field images were alive.

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